Measuring Body Composition: Part 1
Consistently in the comments section of each article there has been at least one question asking how I suggest people measure body composition; as promised I’m finally going to answer them.
Over the next two articles, I want to look at various methods of determining ‘body composition’ (you’ll understand why I’m putting that in quotations in a second) that are available. These range from low- to high-tech and from extremely useful to useless (or at least impractical).
Somewhat arbitrarily, I’m going to divide the different methods into two distinct categories; today I want to talk about measurement methods that don’t strictly measure body composition (in terms of the proportion of fat and lean body mass you have) but which may still have use in tracking changes. On Friday, I’ll look at the ‘truer’ body composition measurement methods.
Even if the methods I’m going to discuss today aren’t ‘true’ ways of measuring body composition, I still think they can be useful; if nothing else since they tend to get trotted out a lot in the media, this article will give you a background to know if what is being talked about is correct or not.
Certainly the lowest tech method of seeing what’s going on with your body is the mirror; and while it doesn’t measure any aspect of body composition, that doesn’t make it useless. At the very least, you can usually look in the mirror (naked, or semi-clothed, mind you) and get a rough idea if you’re underweight, overweight or just about right (whatever those terms might actually mean).
At the very least, you can determine if you’re happy with the way that you look. That is, if you can be honest with yourself. This is not always a safe assumption.
The problem is that we tend to see what we want to see, good or bad. Anorexics see a fat person where a skinny person is standing, and some bodybuilders see a skinny person where a muscular person is standing. Some researchers call this ‘reverse anorexia’, ‘body dysmorphia’ or ‘bigorexia’ (I find that last term really stupid for some reason).
Without getting into a huge tangent about how we perceive ‘reality’, the fact is that our brains lie to us sometimes and we don’t always see reality. This makes the mirror useful but you have to be careful.
I should note that folks can often find magic mirrors; there seems to be one in every gym that makes people look drastically better than they actually do. The lighting is just right, the mirror of whatever quality, that people see definition that doesn’t exist and that sort of thing. If someone could figure out what physical characteristics make up these magic mirrors, they could make a million dollars selling it to dieters and bodybuilders alike. For athletes in the physique sports, these magic mirrors can add up to a lot of disappointments on contest day.
Basically, the mirror, while good, is subject to normal human frailties in being honest with ourselves. I’d rarely recommend it as the sole mode of tracking progress, there’s just too many possibilities for people to go screwy. Use it but with caution.
In a semi-related vein, I should probably mention the use of photos to track progress in body composition. Many coaches recommend taking pictures (front, back, side) to keep a visual comparison of progress over time. Basically, you can put the pictures next to one another and see visual changes over time.
This actually avoids another huge problem inherent to the mirror: when you pose in front of them daily (admit it, you do), the small changes that may be occurring may not be visible. In contrast, if you take pictures every 4 weeks, the changes should be large enough to show visually. I’d note that it’s critical that, if you use the picture method, that you be consistent. Take them in the same lighting, wearing the same clothes, with the camera the same distance from you every time. If you don’t do this, it makes it much harder to tell if real changes are occurring.
For years and years and years dieters focused primarily on changes in scale weight. If the scale went up, that was bad (unless weight gain was the goal); if it went down, that was good (assuming weight loss was the goal). Of course, we know now that things are a lot more complicated than that and now we know to focus on body composition (discussed in more detail in What Does Body Composition Mean?).
In pretty much all of my books, I go into a rather length discussion of body weight vs. body composition and weight vs. fat loss. You can go read the article on the site if you’re still unclear but the short-version is that your total weight is made up of every part of you: fat, muscle, brain, organs, bone, fluid, undigested food in your gut, etc.
In general, when the goal is body re-composition, you’re looking to lose fat, gain muscle or some combination of the two.
When you just ‘lose weight’, you don’t know what you actually lost. Was it fat, muscle, water, you had a huge bowel movement? The standard bathroom scale can’t tell you.
I would note that, for people carrying a lot of fat, changes in scale weight will generally scale with changes in true fat (excepting the initial water weight loss, which can be considerable in large individuals). That is, typically, of the total weight loss in a very fat individual, 90% or so will be fat. So changes in scale weight are a fairly good indicator of changes in fat mass.
For leaner individuals, this stops being the case. Muscle loss can make up 1/4-1/3rd of the total weight loss under some conditions, just looking at scale weight by itself doesn’t provide enough information; the scale MUST be used with another method to accurately track changes.
I should at least mention the supposed ‘body fat’ scales such as Tanita while I’m at it; there are expensive scales that are supposed to estimate true body fat percentage and body composition using a method called Bio-electrical Impedance Analysis (BIA); I’ll talk about them on Friday.
Body Mass Index (BMI)
The BMI is probably the current favorite method to measure ‘body composition’, especially in large groups. The reason for this is that it’s easy, if you have height and weight, it’s a quick calculation to get BMI. Essentially, BMI is like the old optimal height-weight charts that the insurance companies used back in the day but in nifty graphical form.
Now, in the average, non-athletic folks, BMI is actually a decent indicator of overall health with both high and very low BMI’s correlating with various health risks. I’m not saying it’s perfect but it is decent. Please read that sentence again in case you’re unclear on what I said.
In fact, it actually turns out that BMI can be used to get a rough indicator of body fat percentage (that is true body composition), I use this method in both The Rapid Fat Loss Handbook and A Guide to Flexible Dieting. Again, I’m not saying it’s perfect or 100% accurate but it will get people within shooting distance. For non-lean individuals, that’s usually good enough.
However, in athletic individuals (who tend to bitch about BMI a LOT on the Internet), BMI is basically useless and I want to explain why. The basic problem is that, outside of the method in my books, BMI doesn’t actually distinguish between fat and muscle mass. All it does is relate weight and height and higher numbers are bad (very low numbers are also bad).
But, this misses the whole point of body composition as a 200 pound individual at 10% body fat and a 200 pound individual at 30% body fat are clearly not identical. The first is a lean athlete, the second is not. And relative health risk will likely be very different. But BMI will say that they are identical in terms of their relative health risk or what have you.
But this is pretty much a big part of why it works just fine for the non-training population: you simply don’t see individuals who aren’t training carrying a ton of muscle mass when their weight is high. Not in general anyhow. So, in that population, BMI will give a good indicator of how much fat someone is carrying and, by extension, relative health risk. I hope that makes sense
Tangentially, I should note that some researchers feel that the BMI/height-weight charts are unrealistic for most people or provide unrealistic expectations (e.g. the average overweight individual won’t ever reach ‘normal’ BMI levels and the charts will have a negative impact). Research has consistently shown that even a 10% reduction in body weight carries health benefits so even if overweight individuals can never reach a ‘normal’ BMI, that doesn’t mean all is lost.
In any case, back to BMI. As noted above, in relatively inactive, non-training populations, BMI gives at least a rough indicator of health risk. A BMI > 25 kg/m2 is considered overweight, > 30 kg/m2 is obese. Higher numbers correlate with more health risks. So do BMI’s that are excessively low (indicating severe underweight or eating disorders).
If you want to know your BMI, there’s a calculator here:
As mentioned, non-athletic folks can even use their BMI to get a rough estimate of body fat percentage (the conversion charts are in both books mentioned above).
Athletic folks shouldn’t even consider using BMI for any application. Not to determine relatively health risk and not to estimate body fat percentage. They must use another method.
Waist/Hip ratio (WHR)
While early research into health and body composition/body fat focused primarily on total body fat levels, it became clear fairly early that not all fat is the same in terms of the impact it has on overall health and health risks.
Simplistically, fat on the body can be divided into several different ‘types’. I actually described five different types in The Stubborn Fat Solution but I’m only going to talk about two here: subcutaneous and visceral fat.
- Subcutaneous fat: This is the fat that you can see and most are worried about when they want to ‘lose fat’. It’s found under the skin (‘sub’ = under; ‘cutaneous’ = skin) and comprises something like 40-60% of the total fat on your body.
- Visceral fat: This fat is found internally, surrounding the organs and such.
Now, as it turns out, carrying excessive amounts of visceral fat tends to correlate with various health risks including insulin resistance and Syndrome X (aka the metabolic syndrome). It’s still being debated whether visceral fat is a cause or the result of Syndrome X. But the bottom line is that carrying large amounts of visceral fat tends to be related to various health problems. In contrast, having a lot of subcutaneous fat doesn’t carry nearly the same risk.
And that’s where the waist/hip ratio comes in; it’s a quick method to determine relative body fat distribution and therefore health risk. It’s less about body composition and much more to do with overall health risk and fat patterning.
In common parlance, people are typically either pears (skinny upper body/fat lower body which means low visceral fat and high subcutaneous fat) or apples (round in the middle tapering at either end which usually means large amounts of visceral fat).
I’ve never quite figured out what people who carry their body fat very evenly are supposed to be called. A banana?
Generally speaking, women tend to be pears and men tend to be apples. However, extremely fat women will eventually start to accumulate visceral fat (and just become generally round) and post-menopausal women who don’t go on hormone replacement therapy typically show a shift from a pear to an apple shape.
And tying this in with my comments above, Individuals who are apples (having a high waist/hip ratio), because they are carrying more visceral fat, tend to have more health problems than those who are pears.
Excess body fat can always be a health risk but having an apple shape is worse than having a pear shape. For example, it’s thought that one reason women are protected from heart attacks/disease before menopause is because they store most of their fat in their lower bodies, instead of viscerally (around their gut and stomach).
Determining WHR is as easy as getting out the tape measure and throwing it around your waist and hips and comparing the two. Or just look down, if your stomach sticks out more than your hips, your WHR is probably too high. If you want a more accurate method, you can use the calcuator at:
To get a true measure of the WHR.
Another commonly used method of tracking changes in body composition is to measure circumferences, arms, waist, thighs, etc. The method is simple and fast, just throw a tape measure around whatever you want to measure and see what the number is.
Now, there are methods of using circumference to truly estimate body fat percentage. The various equations seem to range from reasonably accurate to horrible. The main benefit, and this will make more sense after Part 2 on Friday is that it’s faster than other methods; groups like the military often use circumference methods since they can be done quickly on a large number of recruits. I’ll discuss circumference methods for estimating body composition more in Part 2 on Friday.
Of more relevance to today’s article, circumference methods are primarily used to track progress on a diet or training program without being used to measure body composition specifically.
Folks trying to gain muscle mass (or improve a certain muscle group) will often use the tape measure to track changes; is the size of the muscle going up, down or not changing (when combined with caliper measures, discussed on Friday, this can be an extremely valuable method of tracking progress).
Dieters can use the method similarly; men may track waist circumference while females might track thigh circumference to see if the diet and training is working as it should. Whether it’s to track overall changes or simply trying to reach some specific goal (e.g. 32 inch waist), circumference measures indicate what’s going on.
I should note that, to be accurate at all, a tape measure has to be used correctly. One issue is that any measurement you make must be made at the same place every time. Folks who do this for a living use very very specific methods of determining where to take measurements. But even small differences in where you take the measurement can give different results. It has to be consistent to be meaningful.
As well, it’s altogether too easy to pull the tape to a different tightness if you’re not careful. Dieters will tend to pull the tape measure a little tighter to get a lower value and folks seeking muscle gain may let it run a little bit loose. Some companies actually sell expensive little tape measures with built-in springs to ensure that the tension on the tape is identical every time.
Basically, circumference methods are good but only if you respect their limitations: you must measure at an identical place every time and you have to pull the tape to the same tension every time. These can be difficult to achieve sometimes. Unfortunately, it would take another article to address both in any useful detail.
So that’s a quick look at what are probably best termed non-body composition methods. The mirror/taking pictures, the good old bathroom scale, Body Mass Index (BMI), Waist/Hip Ratio, and circumference measures can all give some indications about changes in body composition even if they don’t actually tell you what your body fat percentage is (the BMI method I talked about above being one exception). So use them, just with the cautions and caveats above.